Metal wire structure with high-melting-point protective layer and its manufacturing method

ABSTRACT

The present invention presents a metal wire structure with high-melting-point protective layer and its manufacturing method, of which the structure comprising: a core and a protective layer; the core is made of metal, and the protective layer made of metal carbide or metal nitride. The manufacturing method includes the following steps: preparation, discharge and finish. The protective layer is gradually bonded onto the exterior surface of the core until a preset thickness of the protective layer, and then fully covered onto the core through a plating process of discharge reaction at temperature over 5000□. With this design, the present invention has advantages and efficacies such as: without generation of silicide and producing protective effects.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates generally to a metal wire structure withhigh-melting-point protective layer and its manufacturing method, andmore particularly to an innovative one which prevents the generation ofsilicide and produces protective effect.

2. Description of Related Art

The conventional Hot Wire Chemical Vapor Deposition (HWCVD) and PlasmaEnhanced Chemical Vapor Deposition (PECVD) are widely applied to themanufacturing processes of various films, including: semi-conductors,liquid crystal display (LCD) panels and solar panels, helping to form athin film on a substrate. Such film is made of Amorphous Silicon (a-Si)or other components (depending on the reactant gases supplied).

The major disadvantages of PECVD include: low deposition rate, lowproductivity, longer deposition time and cost. The disadvantages ofHWCVD include: difficult to control the concentration of free radical orthe filament temperature, and lower film quality.

FIG. 1 depicts a hybrid chemical vapor deposition combining HWCVD andPECVD (patent No. WO 2009/2009499). Of which, a closed reaction chamber810 comprises: a reaction space 820, a plasma generating unit 830, a hotwire device 840, a substrate 850, a substrate carrier 860, a heater 870,a substrate feeder 875 and a substrate discharger 880. The plasmagenerating unit 830 is used to generate plasma-excited atoms of vaporchemicals, and the hot wire device 840 is used to generatethermally-excited atoms of vapor chemicals. For instance, the mixture ofhydrogen (H₂) and silicon hydride (SiH₄) is fed into the reaction space820 at 1:100; the hot wire device 840 is heated to 1850° C., the plasmagenerating unit 830 generates the energy of 25 w/100 cm² for thesubstrate, and the heater 870 maintains the temperature of 400° C. Withthe use of HWCVD and PECVD, a-Si film can be generated on the substrate850.

FIG. 2 depicts another conventional HWCVD technique (patent No.EP1986242A2), which comprises: a reaction chamber 91, a gas feed portion92, a direct current (DC) power supply 93, a catalytic hot wire 94, anexhaust valve 95, a carrier platform 96 and a heater 97. The carrierplatform 96 is provided with a bottom layer 920, which can be heated bythe heater 97; a film 910 is gradually formed on the bottom layer 920.

However, both hot wire device 840 and catalytic hot wire 94 are made ofpure tungsten; when silicon hydride (SiH₄) is filled into the reactionspace 820 and the reaction chamber 91, and the temperature of hot wiredevice 840 or catalytic hot wire 94 hasn't reached the melting point ofsilicon (about 1410° C.), the gas will contact with the hot wire device840 or catalytic hot wire 94, but cannot be fully decomposed, with someresidual gas left on the surface of hot wire device 840 or catalytic hotwire 94. Then, the silicide (e.g. tungsten silicide) is formed, leadingto change of the filament resistance. Take catalytic hot wire 94, forexample, FIGS. 3A and 3B depicts the outside view of the catalytic hotwire 94 without and with silicide respectively, whilst FIGS. 4A and 4Bdepicts the partially enlarged sectional view of the surface ofcatalytic hot wire 94 without or with silicide respectively. It can beclearly seen that, when silicide 941 is formed on the surface of thecatalytic hot wire 94, silicide 941 may generate many cracks 942 due toexpansion and contraction, as the surface temperature of the catalytichot wire 94 is at normal temperature in idle state, or at 1850° C. inoperating state. In addition, when the silicide 941 is fully coveredonto the catalytic hot wire 94, the function of the catalytic hot wire94 will be lost, affecting the process of hot wire chemical vapordeposition seriously.

Hence, it is important to know how to prevent generation of silicidewith fed gas when the temperature of tungsten filament (either hot wiredevice 840 or catalytic hot wire 94) increases from normal temperatureto 1850° C.

Thus, to overcome the aforementioned problems of the prior art, it wouldbe an advancement if the art to provide an improved structure that cansignificantly improve the efficacy.

SUMMARY OF INVENTION

The object of the present invention is to provide a metal wire structurewith high-melting-point protective layer and its manufacturing method,which prevents the generation of silicide and produces protective effectto resolve the shortcomings of prior art.

In order to achieve the above mentioned object, this invention isprovided. A manufacturing method of metal wire structure withhigh-melting-point protective layer comprising the following steps:

preparation step: preparing a core and a discharge device, of which thecore in a threaded shape is made of metal material; the discharge devicebeing provided with a positive electrode, a negative electrode, adischarge reaction tank, a discharge processing medium, an electrodefixed portion and a discharge reaction member; the discharge processingmedium being placed into the discharge reaction tank, the electrodefixed portion being used to fix the core, which is linked to thenegative electrode; the discharge reaction member made of metal beinglinked to the positive electrode; a preset discharge gap being definedbetween the core and the discharge reaction member, and filled with thedischarge processing medium; the discharge processing medium consistingof either carbon atom or nitrogen atom;

discharge step: the discharge device being activated to enableelectrical discharge of the core and the discharge reaction member; alocal temperature in this discharge process being over 5000° C., sometal atoms of the core impinging dispersedly on an exterior surface ofthe discharge reaction member, meanwhile the metal atoms of thedischarge reaction member being combined with atoms in the dischargeprocessing medium, and impinging dispersedly on the exterior surface ofthe core, so a protective layer being gradually formed on the exteriorsurface of the core;

finish step: a metal wire structure with high-melting-point protectivelayer being made which comprises:

-   -   a core which is made of metal material and is shaped as a        thread;    -   a protective layer which is made of either metal carbide or        metal nitride; the protective layer being gradually bonded onto        an exterior surface of the core until a preset thickness, and        then fully covered onto the core through a plating process of        discharge reaction at temperature over 5000° C.

About the structure of this invention, a metal wire structure withhigh-melting-point protective layer comprises:

a core which is made of metal material and is shaped as a thread;

a protective layer which is made of either metal carbide or metalnitride; the protective layer being gradually bonded onto an exteriorsurface of the core until a preset thickness, and then fully coveredonto the core through a plating process of discharge reaction attemperature over 5000□.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of the first prior art.

FIG. 2 shows a schematic view of the second prior art.

FIG. 3A shows a perspective view that no silicide is formed on thesurface of conventional catalytic hot wire.

FIG. 3B shows a perspective view that silicide is already formed on thesurface of conventional catalytic hot wire.

FIG. 4A shows a partially enlarged sectional view that no silicide isformed on the surface of conventional catalytic hot wire.

FIG. 4B shows a partially enlarged sectional view that silicide isalready formed on the surface of conventional catalytic hot wire.

FIG. 5 is a view illustrating the present invention.

FIG. 6 shows a flow chart of the present invention.

FIG. 7 shows a schematic view of the processing system of the presentinvention.

FIG. 8 shows a partially enlarged view of FIG. 7.

FIG. 9A shows a schematic view of the first discharge process of thepresent invention.

FIG. 9B shows a schematic view of the second discharge process of thepresent invention.

FIG. 9C shows a schematic view of the third discharge process of thepresent invention.

FIG. 10 shows a schematic view that the structure of the presentinvention is applied to HWCVD device.

FIG. 11 shows another schematic view that the structure of the presentinvention is applied to HWCVD device.

FIG. 12 shows a partially enlarged view that the structure of thepresent invention is applied to HWCVD device.

FIG. 13 shows an appearance view of common tungsten filament.

FIG. 14 shows an appearance view of the present invention.

FIG. 15 shows a partially enlarged view of the present invention.

FIG. 16 shows an EDS analysis view of the protective layer of thepresent invention.

FIG. 17 shows a schematic view that common tungsten filament is heatedto 600° C.

FIG. 18 shows a schematic view that the present invention is heated to600° C.

FIGS. 19A, 19B, 19C and 19D show the surface the metal wire structurewith high-melting-point protective layer after completion of dischargethat is amplified to 25 times, 50 times, 100 times and 200 timesrespectively.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a metal wire structure withhigh-melting-point protective layer and its manufacturing method.Referring to FIG. 5, the metal wire structure 100 of the presentinvention with high-melting-point protective layer comprises:

a core 20, which is made of metal material and is shaped as a thread;

a protective layer 30, which is made of either metal carbide or metalnitride; the protective layer 30 is gradually bonded onto the surface ofthe core 20 until a preset thickness, and then fully covered onto thecore 20 through a plating process of discharge reaction at temperatureover 5000° C.; moreover, the cross section of the core 20 is of round(shown in FIG. 5), rectangular, flat or other geometric shapes.

Referring to FIG. 6, the manufacturing method of the present inventionincludes the following steps:

preparation step 11: preparing a core 20 and a discharge device 40, ofwhich the core 20 in a threaded shape is made of metal material; thedischarge device 40 is provided with a positive electrode 41, a negativeelectrode 42, a discharge reaction tank 43, a discharge processingmedium 44, an electrode fixed portion 45 and a discharge reaction member46; the discharge processing medium 44 is placed into the dischargereaction tank 43, the electrode fixed portion 45 is used to fix the core20, which is linked to the negative electrode 42; the discharge reactionmember 46 made of metal is linked to the positive electrode 41; a presetdischarge gap S is defined between the core 20 and the dischargereaction member 46, and filled with the discharge processing medium 44;furthermore, the discharge processing medium 44 consists of eithercarbon atom or nitrogen atom;

discharge step 12: the discharge device 40 is activated to enableelectrical discharge of the core 20 and the discharge reaction member46; referring to FIGS. 9 A, 9B and 9C, the local temperature in thisdischarge process is over 5000° C., so metal atoms of the core 20impinge dispersedly on an exterior surface of the discharge reactionmember 46, meanwhile the metal atoms of the discharge reaction member 46are combined with the atoms of the discharge processing medium 44 (i.e.carbon or nitrogen atoms), and impinge dispersedly on the exteriorsurface of the core 20, so a protective layer 30 is gradually formed onthe exterior surface of the core 20;

finish step 13: a metal wire structure 100 with high-melting-pointprotective layer is made which comprises:

a core 20, made of metal material and shaped as a thread;

a protective layer 30, made of either metal carbide or metal nitride;the protective layer 30 is gradually bonded onto the surface of the core20 until a preset thickness of protective layer, and then fully coveredonto the core 20 through a plating process of discharge reaction attemperature over 5000° C.

More specifically, the core 20 is made of W, Pt, Pd, Mo, Ti, Nb, Ta, Co,Ni, Cr, Mn or tungsten alloy, platinum alloy, palladium alloy,molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy, cobaltalloy, nickel alloy, chrome alloy, or manganese alloy. The protectivelayer 30 is made of either metal carbide or metal nitride containing W,Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn, tungsten alloy, platinum alloy,palladium alloy, molybdenum alloy, titanium alloy, niobium alloy,tantalum alloy, cobalt alloy, nickel alloy, chrome alloy, or manganesealloy (e.g.: TiC, TaC, TiN, WC and CrC).

In addition, the core 20 and the protective layer 30 can be made ofmaterials with similar thermal expansion coefficient so as to preventthe bonding relation due to thermal expansion. For example: when thecore 20 is made of tungsten, the expansion coefficient is about 4.6(10⁻⁶/° C.), and the protective layer 30 can be made of WC or TiC, withthe thermal expansion coefficient of WC approx. 3.7 to 5.7 (10⁻⁶/° C.),and that of TiC approx. 5.5 (10⁻⁶/° C.), showing a similar thermalexpansion coefficient of the core 20 and the protective layer 30.

It is assumed that the discharge reaction member 46 is made of titanium,and the discharge processing medium 44 is a solution containing carbonatom; the key feature of the present invention lies in the dischargemechanism, whereby a temperature over 5000° C. is generated during thedischarge process, so that the titanium atom of the discharge reactionmember 46 and the carbon atom in the discharge processing medium 44 arecombined into TiC impinging on the electrode (tungsten is assumed), andclosely bonded onto the electrode to form gradually a thin TiCprotective layer. The bonding process among atoms presents excellentcompactness. In other words, when the metal wire structure 100 of thepresent invention with a high-melting-point protective layer (it isassumed that the core 20 is made of tungsten), the operating temperatureof the energized tungsten filament is about 1850° C.˜2100° C., muchlower than the temperature generated by TiC protective layer. So, theTiC protective layer no longer reacts with the reactant gas (e.g.silicon hydride or hydrogen), nor generates silicide. Certainly, thedischarge processing medium 44 is also a kind of gas containing nitrogenatom (e.g.: N₂), so that the carbon and nitrogen atoms are combined intoTiN impinging on the electrode, and closely bonded onto the electrode toform gradually a thin TiN protective layer.

In addition, as for the metal wire structure 100 with high-melting-pointprotective layer after completion of discharge, the surface is shown inFIGS. 19A, 19B, 19C and 19D, wherein the surface is amplified to 25times, 50 times, 100 times and 200 times.

The present invention can be applied to a HWCVD device (namely, thecatalytic hot wire 94 of prior art can be replaced as a metal wirestructure 100 of the present invention with a high-melting-pointprotective layer); referring to FIGS. 10, 11 and 12, when siliconhydride (SiH₄) (shown by the arrow) is filled into the reaction chamber91, and the temperature of the core 20 hasn't reached the melting pointof silicon (about 1410° C.), the protective layer 30 can protect thecore 20 not to contact with gas (the melting point of the protectivelayer 30 is over 5000° C.). Hence, it helps to resolve the shortcomingsof prior art that gas cannot be fully decomposed, with some residual gasleft on the surface of catalytic hot wire 94 (i.e. generation ofsilicide).

The products of the present invention can be used in some applicationssuch as:

[a] Example one: the metal wire structure with high-melting-pointprotective layer is heated up, then the reactant gas passing through thesurface of the protective layer 30 is heated to generate free radical,allowing for technical applications for cleaning the surface of Si, Aland TiN, as well as copper film (i.e. Cu film), etc. The reactant as canbe selected optionally from any group of hydrogen (H₂), ammonia (NH₃),silicon hydride (SiH₄), hydrazine (NH₂NH₂) and water (H₂O). Forinstance, if the reactant gas is hydrogen (H₂) or vapor (H₂O), it cangenerate free radical of H atom, if the reactant gas is ammonia (NH₃),it can generate free radical of NH and NH₂ atoms.

[b] Example two; the metal wire structure with high-melting-pointprotective layer is heated up, then the reactant gas (CH₄) passingthrough the surface of the metal wire is heated to generate free radical(C atom, etc), allowing for DLC (Diamond-Like Carbon) plating.

The actual test results of the present invention are described below:

FIGS. 13 and 14 depict separately the perspective view of conventionaltungsten filament and the present invention. FIG. 15 depicts a partiallyenlarged view of the present invention, wherein 2˜3 μm protective layer30 of the present invention can be clearly observed.

FIG. 16 depicts EDS (Energy Dispersive Spectrometer) analysis of theprotective layer 30, of which carbon atom is 67%, titanium atom 3% andtungsten atom 30%, proving the covering effect of the protective layer30.

Vickers hardness test results indicate that, the hardness of commontungsten filament is HV400, but that of the present invention increasesto HV700; common tungsten filament will be softened when it is heatedelectrically (DC) up to 600° C. (shown in FIG. 17), but the presentinvention lacks of such phenomenon when it is heated up to 600° C.(shown in FIG. 18).

In addition, the temperature distribution of common tungsten filament isshown in Table 1 and FIG. 17 (serial number of positions in Table 1corresponds to that of positions A1˜A14 in FIG. 17). It can be seenthat, the temperature distribution of common tungsten filament isextremely uneven (high temperature concentrated at right side). However,the temperature distribution of the present invention is shown in Table2 and FIG. 18 (serial number of positions in Table 2 corresponds to thatof positions B1˜B14). It can be seen that, the temperature distributionof the present invention is even.

TABLE 1 Temperature distribution of common tungsten filament Serial Noof positions Temperature(° C.) Point A1 596 Point A2 580 Point A3 552Point A4 511 Point A5 492 Point A6 490 Point A7 507 Point A8 518 PointA9 328 Point A10 338 Point A11 57 Point A12 68 Point A13 44 Point A14 42

TABLE 2 Temperature distribution of the present invention Serial No ofpositions Temperature(° C.) Point B1 606 Point B2 600 Point B3 603 PointB4 596 Point B5 598 Point B6 600 Point B7 598 Point B8 577 Point B9 104Point B10 68 Point B11 49 Point B12 33 Point B13 35 Point B14 29

It is proved experimentally that, in an oxygen-bearing environment, ifthe catalytic hot wire 94 of prior art is made of tungsten, and thetemperature is about 1000° C.˜2000° C., wire rupture may occur; but, dueto the protective layer 30, the core 20 of the present invention willnot rupture in an oxygen-bearing environment at 1000° C.˜2000° C.

The advantages and efficacies of the present invention can be summarizedbelow:

1. Without generation of silicide. In the prior art, when siliconhydride (SiH₄) contacts with hot wire device 840 or catalytic hot wire94 whose temperature hasn't reached the melting point of silicon (about1410° C.), the gas cannot be fully decomposed, with some residual gasleft on the surface of hot wire device 840 or catalytic hot wire 94.Namely, silicide 941 is formed. When the silicide 941 is fully coveredonto the catalytic hot wire 94, the function of the catalytic hot wire94 will be lost, affecting the process of hot wire chemical vapordeposition seriously. With the use of discharge processing method, aprotective layer 30 is formed on the exterior surface of the core 20,thus maintaining the function of the core 20 and preventing reaction ofgas with the core 20 against generation of silicide 941.

2. Producing protective effects. In the prior art, the silicide 941 isprone to form many cracks 942 due to expansion and contraction,affecting the function and service life of the catalytic hot wire 94;with the use of protective layer 30, the present invention can preventthe forming of silicide 941 on the core 20 for realizing the protectiveeffects.

The aforementioned description of the preferred embodiments shows thatthe present invention can really meet the above-specified purpose andpatent specifications, so the patent application is claimed herein.

Although the invention has been explained in relation to its preferredembodiment, it is to be understood that many other possiblemodifications and variations can be made without departing from thespirit and scope of the invention as hereinafter claimed.

1. A manufacturing method of metal wire structure withhigh-melting-point protective layer comprising the following steps:preparation step: preparing a core and a discharge device, of which thecore in a threaded shape is made of metal material; said dischargedevice being provided with a positive electrode, a negative electrode, adischarge reaction tank, a discharge processing medium, an electrodefixed portion and a discharge reaction member; said discharge processingmedium being placed into said discharge reaction tank, said electrodefixed portion being used to fix said core, which is linked to saidnegative electrode; said discharge reaction member made of metal beinglinked to said positive electrode; a preset discharge gap being definedbetween said core and said discharge reaction member, and filled withsaid discharge processing medium; said discharge processing mediumconsisting of either carbon atom or nitrogen atom; discharge step: saiddischarge device being activated to enable electrical discharge of saidcore and said discharge reaction member; a local temperature in thisdischarge process being over 5000□, so metal atoms of said coreimpinging dispersedly on an exterior surface of said discharge reactionmember, meanwhile the metal atoms of said discharge reaction memberbeing combined with atoms in said discharge processing medium, andimpinging dispersedly on said exterior surface of said core, so aprotective layer being gradually formed on said exterior surface of saidcore; finish step: a metal wire structure with high-melting-pointprotective layer being made which comprises: a core which is made ofmetal material and is shaped as a thread; a protective layer which ismade of either metal carbide or metal nitride; said protective layerbeing gradually bonded onto an exterior surface of said core until apreset thickness, and then fully covered onto said core through aplating process of discharge reaction at temperature over 5000□.
 2. Themethod defined in claim 1, wherein said discharge reaction member ismade of W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn tungsten alloy,platinum alloy, palladium alloy, molybdenum alloy, titanium alloy,niobium alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy,or manganese alloy.
 3. A metal wire structure with high-melting-pointprotective layer comprising: a core which is made of metal material andis shaped as a thread; a protective layer which is made of either metalcarbide or metal nitride; said protective layer being gradually bondedonto an exterior surface of said core until a preset thickness, and thenfully covered onto said core through a plating process of dischargereaction at temperature over 5000□.
 4. The structure defined in claim 3,wherein said core is made of W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn,tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy,titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickelalloy, chrome alloy, or manganese alloy.
 5. The structure defined inclaim 3, wherein said protective layer is made of metal carbidecontaining W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn, tungsten alloy,platinum alloy, palladium alloy, molybdenum alloy, titanium alloy,niobium alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy,or manganese alloy.
 6. The structure defined in claim 3, wherein saidprotective layer is made of metal nitride containing W, Pt, Pd, Mo, Ti,Nb, Ta, Co, Ni, Cr, Mn, tungsten alloy, platinum alloy, palladium alloy,molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy, cobaltalloy, nickel alloy, chrome alloy, or manganese alloy.